In U.S. Pat. 3,939,745 to Weeks, et. al. an apparatus is disclosed for accomplishing a precision slitting of light gauge coil stock to form multiple continuous lengths of metal wire or ribbon. The slit products obtained are characterized by a cross-sectional area of less than 7.0 .times. 10.sup.-.sup.4 square inch and an aspect ratio of less than 5 with aspect ratio being defined as the ratio between width and thickness. Those products having a square cross-section (i.e., an aspect ratio of one) are generally referred to in the art as "wire", while products which have an aspect ratio of greater than one are commonly referred to as "ribbon".
Although the capability for producing metal wire and ribbon of the aforementioned dimensions by slitting procedures offers a significant economic advantage over other methods of production, an inherent problem which must be overcome is the formation of an undesirable burr on the cross-section of the slit product. For example, when a 10 mil wide steel wire is formed by slitting a 10 mil thick steel strip, the resulting product has a slightly distorted square shaped cross-section due to the presence of burrs along its length. These burrs are formed when adjacent lengths of wire are separated in the slitting operation. Since the burr provides a prominent crack initiation site, it obviously has an adverse effect on the mechanical properties of the slit product. The resulting loss in fatigue resistance is especially harmful in the case of steel products intended for use as reinforcing elements in pneumatic tires.
An apparatus for eliminating the aforementioned burr formation is disclosed in commonly assigned U.S. patent application Ser. No. 623,289 filed Oct. 17, 1975. The apparatus consists of a pair of revolving shaping rolls. One roll is provided with a continuous annular groove having a curved bottom portion. The second roll contains a continuous annular land adapted to engage the groove of the opposing roll so as to force the slit product which is delivered between the rolls into the groove and thereby effect a shaping of the product to eliminate the burr. When in operation, the rolls are in a mechanically fixed engagement. That is, during set up the rolls are engaged until a satisfactory wire cross-section is obtained after which they are locked into place.
Although this apparatus has been successful in the elimination of burr formations, a consistent problem has been an inability to establish and maintain equivalent roller engagement settings from one run to another. The fact that roller engagement will vary from run to run necessitates costly precision during roller manufacture and extra time during set-up. However, even close control of roller diameter and groove depth does not eliminate the engagement variation resulting from variations in the thickness of the slit product being processed.
It is, therefore, an object of this invention to provide an improved roll shaping apparatus for eliminating the burr from slit metal products.
It is a further object of this invention to provide an improved roll shaping apparatus for eliminating the burr from slit metal products wherein the roll engagement can be controlled in a consistent and reproducible manner.